In George Orwell's dystopia "Nineteen Eighty-Four", Newspeak was the corrupted/purged language everyone was supposed to speak according to the totalitarian dictatorship which ran everything. Words with subversive potential and those which had unclear meanings were eliminated, along with references to the past. The attempt was to bring language, and therefore thought, into line with the wishes of the rulers.

It is also used to refer to any instance of politically-invented language put out through apparatuses of propaganda and social control or by spindoctors.

This doesn't mean you shouldn't make up new words. Nor does it mean that every political or invented word should be suspect. The point is that new words should expand meaning, not contract it. If a word is used to cover up abuses by the powerful or to manipulate people in favour of the existing regime, it's Newspeak.

Language of Ingsoc, a fictional empire in the book 1984. The language was meant to eliminate all words deemed as nonsence, and was created to eliminate certain words, so dissent could not be expressed nor communicated

this would eliminate words of "excess"
and negative words would be replaced with its positive antonym with the prefix of -un. To stress an emotion, the prefixes of -double, -plus were added. The more prefixes, the more expression is placed in the word.

Contrived language of Oceania from George Orwell's "1984." It uses many English words, albeit with a greatly simplified vocabulary and sentence structure. The elimination of synonyms and antonyms helped this process. It was created in attempt to influence the thought of Oceania's citizens and make it impossible to express thoughts dangerous to Ingsoc (Newspeak for English Socialism). Today this is recognized as political correctness.

Examples:

Minitruth="Ministry of Truth" (Oceanian propaganda ministry)
Ungood="bad"
Doubleplusgood="excellent"
Doublethink=the ability to hold two contradictory thoughts at a time
B-B="Big Brother", ie the State

These translations give a rough estimate of some general rules when using Newspeak.